Oil well cementing shoe



Sept. 1l, 1962 A. K. KLINE OIL WELL CEMENTING SHOE 2 Sheets-Sheet 1Filed Jan. 28, 1960 INVENTOR. ALBERT K. KLNE BY ya zz@ ATTORNEY Sept.11, 1962 A. K. KLINE oIL WELL CEMENTING SHOE:

Filed Jan. 28., 1960 United States Patent O 3,053,322 H., WELL CEMENTWGSHOE Albert K. Kline, 5741 S. 70th E. Ave., Tulsa 4S, Okla. Filed Jan.28, 1960, Ser. No. 5,260 7 Claims. (Cl. 166-l84) The present inventionrelates to structure for sealing a cementing shoe to the side of an oilwell bore. More speciiically, the invention relates to a novel packerfor a cementing shoe and structure for operating the packer.

It is common to mount a shoe of deformable, resilient, material, usuallyrubber, on the tubular body of a cementing shoe and deform this sleeveof material until it engages the sides of the well bore. After theannulus between the body and bore is positively sealed in this manner,an opening in the side of the shoe body is uncovered and cementingmaterial pumped down the tubing which carries the shoe on the tube endand into the annulus above the deformed packer on the shoe.

These packing sleeves have been set by iluid pressure acting on a pistonsliding within, or on the outside of, the tubular body. The piston hasbeen linked with the sleeve, through a more or less complex apparatus.Also, the packer sleeve has been held in its deformed position bylocking wedges of Various forms which have added to the complications ofmanufacture and operation of the shoe.

It is a principal object of the present invention to set a cementingshoe packer by direct application of iiuid pressure to the packer.

Another object is to set a cylindrical packing element Without materialalteration of the wall thickness of its cylindrical form.

Another object is to lock the packing element in its set position bymaintaining the fluid pressure in direct application to the element.

Another object is to initially seal the packer from direct contact withfluid pressure within the shoe body and then positively provide accessto the packer for the fluid pressure.

Another object is to initially seal uid pressure, within the shoe body,which fluid pressure is used directly to set the packer and thenpositively provide access to the annulus between the body and bore abovethe packer while positively locking the fluid pressure on the packerafter it is set.

The present invention contemplates a deformable, resilient, packingelement in the form of a sleeve mounted on the external surface of thetubular body of a cementing shoe. One end of the sleeve is fixed to thebody and a piston cylinder is provided for the free end of the sleeve.Fluid pressure is placed within the piston cylinder so as to move thefree end of the sleeve as a piston and buckle the central portion of thesleeve away from the body until the well bore sides are engaged in asealing relation.

The invention further contemplates a valve mounted within the pistoncylinder which prevents the escape of the fluid pressure so the iluidpressure keeps the packer locked in its sealing engagement with the wellbore.

The invention further contemplates piston valves within the tubular bodywhich are moved by the uid pressure to selectively open a port in thetubular body into the piston cylinder, cover the port into the cylinder,and, iinally, open a port in the tubular body above the packer.

Other objects, and advantages of the present invention will becomereadily apparent from the following detailed description of theinvention with specic references to the accompanying drawings in which:

FIG. 1 is a longitudinal section of a cementing shoe embodying thepresent invention disposed within a well bore, with its parts in theirinitial positions;

,. ICC

FIG. 2 s a cross-section of the shoe of FIG. 1 along lines 2 2;

FIG. 3 is a cross-section of the shoe of FIG. 1 along lines 3-3;

FIG. 4 is a longitudinal section similar to FIG. 1, disclosing a valveshift within the shoe body and the packer being positioned; and

FIG. 5 is a longitudinal section similar to FIGS. l and 2 disclosing theshoe packed off within the Well bore and the side ports opened to thewell bore.

FIGS. 1, 4 and 5 are used to illustrated the over-all operation of thecementing shoe structure in which the invention is embodied. The packeris shown mounted on the wall of the shoe as the shoe is run in the boreof an oil well. The positions given the internal parts of the shoe arethen illustrated in other drawing figures as energy is applied to movethe packer into sealing position between the shoe wall and the wellbore.

FIG. l specifically shows the parts `of the shoe in their initialpositions as the shoe is lowered into a well bore. The well bore ll isgiven only perfunctory illustration as the fact is developed that thebore is a hole, substantially circular in cross-section, the walls` ofthe hole being engaged by the packer of the shoe.

The shoe is lowered a predetermined `depth in well bore 1. The string ofpipe, carrying the shoe on its end, is indicated at 2. The end of pipe 2is threaded and engaged to a coupling 3. The body 4 of the shoe is thenthreaded up into coupling 3.

Body 4- is in the form of a tube. The various parts of the shoe, movableand fixed, are mounted directly on this body tube. A coupling 5 isthreadedly ymounted on the lower end of shoe body 4. A guide nose 6 isthreaded up into coupling 5, this member fixing the longitudinaldimension of the shoe assembly.

The shoe as a whole, considering the parts related as described to thispoint, has a continuous passageway provided from the pipe string 2 tothe well bore below the shoe. All the parts within tubular body l haveaxial ybores to provide this passageway, and guide nose 6 has a seriesof holes 7 giving access from pipe 2 to the bore below the shoe.Therefore, as string 2 is run in bore ll, and before the packer of theshoe is set, the well may be worked with fluids as desired. After thecernenting program is completed on the bore above the shoe, after it ispacked to the well bore, the various parts within tubular body 4 may beremoved with a drill and the well bore 1 below the shoe worked asdesired, through the pipe string 2.

The packer of the cementing shoe is made of deformable material in theform of a cylinder, mounted on the external wall of tube body 4. Packerlll, as a sleeve, is fixed securely by its lower end to the body 4l.Specifically, the lower end of packer 10 is clamped to the body tube bythe upper end of coupling 5 overlapping the packer. A counter bore at11, from the upper end of coupling 5 forms the overlapping recessbetween coupling 5 and body 4 in which the lower end of packer 10 seats.As a sealing provision, an 0-ring 12 is positioned between packer l0 andthe well of body 4.

The present invention provides for fluid pressure to be applied downpipe string 2, directly upon sleeve packer 10 in such a way that thesleeve buckles outward, toward the walls of bore 1 and into sealingengagement therewith. The lower end of packer 10` is held in iixedrelation to the I'body pipe 4. Therefore, the upper end of the packermust be moved by the fluid pressure in buckling the portion of thesleeve intermediate its ends into sealing position against the borewall.

The prior art has illustrated various mechanical connections fortransmission of fluid pressures internal of `a chamfer cut 15' on theinner edge of the sleeve.

pipe strings on to deformable packers. However, the present inventionadvances the novel concept of moving the upper end of the sleeve as apiston within a cylinder to bulge, or buckle, the section of the packerintermediate its ends. This action of the sleeve form of packer isobtained without substantial decrease of the lwall thickness of thepacker. The full `strength of the cylinder of deformable material isthereby retained. Further, provisions are made to hold the fluidpressure on the packer end, pistoned in its cylinder, after the fluidpressure within pipe string 2 has been removed. The retention of fluidpressure on the packer keeps it permanently set, regardless ofsubsequent activity carried on within pipe string 2.

In forming a piston housing over the upper end of packer 10, housingshell 13, having a generally cylindrical form, is extended from ashoulder 13A on body 4, down over the upper end of sleeve-packer 1f).The main portion of housing shell 13 is spaced from the outer surface ofbody 4 to provide an annulus into which the upper portion of packer 10extends. The upper end of housing shell 13 is extended inwardly to restbeneath shoulder 13A and engage the outer surface of body 4 with asliding llt.

An O-ring 13B seals in the inwardly extending upper end of housing 13 tobody 4 in providing a piston cylinder which is closed at its upper endand which receives the packer 10. The upper end of packer 10 has itswall thickness sized to give a sliding t in the piston cylinder formedbetween the external wall of tubular body 4 and the inside surface ofhousing shell 13. Fluid pressure is conducted into this piston cylinderfor direct application to the upper end of packer 10. An O-ring 14 iscarried in a groove cut in the external surface of packer l so as tofunction as a seal between the packer and housing shell 13. Sealed intothe cylinder of housing shell :13 by O- rings 12, 13B and 14, the uidpressure is effective in moving the upper end of the packer toward itslower end. The result of moving the upper end of the packer toward thelower end is to buckle the packer of deformable material outward, intosealing engagement with the walls of Well bore 1.

FIG. 2 is used to illustrate more clearly the relation between housingshell 13, packer and tubular body 4. Also, FIG. 2 relates the structurein the combination which directs the fluid pressure force outward, fromthe body 4 wall, and upon the packer 10.

FIG. l shows the upper end of the packer 10 as having Fluid pressurewithin the chamber is effective on the lip of the packer 10 formed inthis manner to energize the seal the packer end forms with the internalsurface of housing shell 13. Further, the fluid pressure is directedbetween the internal surface of packer 10 and the outside wall oftubular body 4. F-IG. 2 illustrates a series of grooves 16 cutlongitudinally in the internal wall of packer 10, from charnfer 15 to apoint just above O-ring 12. These grooves 16 conduct the fluid pressurein the piston housing 13 behind packer 10 in order that it will exertits force radially outward from the body 4, against packer 10. Thus, notonly is there the force of the fluid pressure applied longitudinally,against the end of packer 10, but the force of this same fluid pressureis applied radially out- Ward to move the center section of the packerinto sealing engagement with the Wall of well bore 1. FIGS. 4 and 5 maybe referred to in illustration of the progressive positioning of thepacker under the force of this fluid pressure.

The fluid pressure of pipe string 2 is conducted into the pistonchamber, formed with housing shell 13, through openings `17 in the wal-lof tubular body 4. FIG. 3 shows holes 17 to be preferably four innum'ber and spaced evenly in a horizontal plane. Within the pistoncylinder of housing shell 13, these holes 17 are `covered by a ring 18of expansible material, preferably of the same material used forpacker'lfl. As fluid pressure within body tube 4 is applied to holes 17,ring l is expanded enough to permit fluid to flow from under the ringand into the piston cylinder into direct application to the packer.However, `when the fluid pressure in pipe string 2 and the shoe body isremoved, ring 18 contracts to effectively seal holes 17, trapping thefluid pressure in the piston cylinder on the packer. The external edgesof ring 18 are given slight chamfer cuts at 19 to provide lips whichwill be energized by the fluid pressure in the piston cylinder toeffectively seal across lopenings 17.

When fluid pressure is admitted to the piston cylinder, the operation of`the packer is simple, clear and understandable. However, the structurefor bringing the iluid pressure from pipe string 2 into the pistoncylinder must also be understood as a function of the complete cementingshoe combination.

One desirable function of the shoe structure is isolation of the pistoncylinder from the pipe string interior while the shoe is positioned inthe well bore 1 at its predetermined packing position. This isolation isinsured during this operation by valve ring 20. This piston ring 2l) isa simple sliding member within the tubular `body 4 which bridges andseals across holes 17.

Valve ring 2t) does not directly seal across holes 17 in the wall oftubular body 4. Specifically, shift valve 21 is provided, as acylindrical member, having a sliding fit within the walls of tubularbody 4. Holes 22 are in the wall of shift valve 21, aligned with holes17 of body 4. A manifold groove 23 is formed in the outside wall ofvalve 2l, joining all holes 22 and holes 1'7. Further, O-ring seals areprovided in grooves above and below the holes 22 and groove 23 to sealto the inside wall of body 4. With valve ring 20 sealed to the insidewall of shift valve 21, valve ring 26 initially blocks any iluid withinthe body 4 and pipe string 2 from entering the piston chamber throughholes 17 and 22. The advantage and desirability of this isolationfunction of valve ring 20 is to prevent any drilling mud or other fluidswithin well hole 1 from clogging and fouling the holes 17 and 22 andpiston chamber as the shoe is lowered through these fluids to itspredetermined position. Once in position, the fluids may be yblown fromthe shoe by gas and the valve ring shifted to a location below thealigned holes 17 and 22 to give the fluid pressure supplied string 2access to the packer as a piston.

Valve ring 2@ is initially assembled in the bore of shift valve 21 withshear screws 25 holding the ring in its sealing position. The shearscrews, or pins, are placed in holes evenly spaced in the walls of valvering 20 and shift valve 21. FIG. 3 should Ibe specifically referred toas disclosing how the shear member holes are alternated in the wall ofvalve 21 with aligned holes 17 and 22, in the same Plane.

Shear screws 25 are 'failed by fluid pressure applied to the valve ring20. The pressure is made effective 0n the ring by closing the centralpassage through the ring. The passage is specifically closed by droppinga valve member 26 in the form of a ball down pipe string 2 so it willrest on seat 27. Once ball 26 is on seat 27, the fluid pressuresubsequently applied `to pipe 2 from a source at surface level willdevelop a force on both ball 26 and ring 20. Raised to a predeterminedfirst value, `the force of the fluid pressure fails the screws 25 inshear. Valve ring 20 shifts its position to shoulder 28 which is formedon the lower end of shift valve 21. The lrepositioning of valve ring 20clears aligned holes 17 and 22 as shown in FIG. 4. Check valve ring 18expands and the fluid pressure of pipe 2 is applied to the end of packer10 and behind packer 10 to move it into operative sealing positionagainst well lbore 1 wall.

The fluid pressure of pipe 2 is then raised to a second predeterminedvalue. As the fluid pressure increases to its second value thepositioning of packer 10 is completed. Shear screws 29 are then failedin shear by the second value of the fluid pressure, shifting valve 21downward.

Shear screws 29 are spaced about the walls of shift valve Z1 and tubularmember 4 in aligned holes provided near the top of shift valve 21. Fourof these shear members can be provided, similar to the four shear screws25.

However, the strength of the two sets of screws, in shear,

is materially different so valve ring 20'wil1 be repositioned first. Y

Shift valve 21 is moved downward, under the force of the Huid pressuredeveloped on ball 26, Vring 20 and valve 21 -as a unit. The movementwill continue until shift valve Z1 cornes against shoulder 30 in thewall of body 4. This travel of the valve brings the O-rings 3l and 31Ain a position where they seal openings 17 from the interior of the,shoe. FIG. 5 illustrates this final relation of the parts. The fluidpressure in the piston ychamber is trapped on the packer 10, andopenings 32 in the wall of body 4 permit passage of fluids from pipe 2into the annulus formed between the body `4, yand pipe 2 and the wallsof the well bore 1 above packer 10. Operated in the foregoing manner,the shoe functions to limit the working of the well bore to above theshoe packer until the shift valve 21, valve ring 20, ball 26 and guidenose 6 are drilled out of the shoe.

From the foregoing it will be seen that this invention is one welladapted to attain all of the ends and objects hereinabove set forth,together with other advantages which are obvious and which are inherentto the apparatus. t

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations. This is contemplated by and is within the scope of theclaims.

` As many possible embodiments may be made of the invention withoutdeparting from the scope thereof, it is to be understood that all matterherein set forth or shown in the accompanying drawings is to beinterpreted as illustrativc and not in a limiting sense.

' The invention having been described, what is claimed is:

l. A cementing shoe for an oil well including,

a body in the form of a tube adapted to be carried in the well bore onthe end of a pipe string,

a packing element in the form of a cylinder mounted on the externalsurface of the body tube wall and fixed by one end to the body tubewall,

a housing shell in the form of a cylinder mounted about the outersurface of the body tube wall and spaced from the body tube wallthroughout substantially its entire length and extending inwardly fromone of its two ends to form a seal with respect to the body tube wall,

said shell forming a piston cylinder sized to receive the free end ofthe packing element with a sliding tit while said packing element issealed fluid tight with respect to the housing shell, said packingelement having a passage on its internal surface extending from its freeend by which fluid pressure is applied between the packing element andbody tube wall,

a source of lluid pressure connected to the interior of the housingshell for direct application to the free end of the packing element inthe piston cylinder and to the center section of the packing elementbetween the wall of the body tube and the packing element through saidpassage,

'p whereby the free end of the packing element will be moved toward thefixed end as a piston within the cylinder of the housing shell and the`center section of the packing element will be simultaneously buckledaway from the body wall without substantial decrease in cross-sectionalthickness of the packing element until a seal is made between the sidesof the well bore and the packing element.

2. A cementing shoe for an oil well including,

a body in the form of a tube adapted to be carried in the well bore onthe end of a pipe string,

a packing elernent in the form of a cylinder mounted on the externalsurface of the body tube wall and fixed by one end to the body tubeWall,

a housing shell in the form of a cylinder mounted about the outersurface of the body tube wall and spaced from the body tube wallthroughout substantially its entire length and extending inwardly fromone of its two ends to form a seal with respect to the body tube wall,

said shell forming a piston cylinder sized to receive the free end ofthe packing element with a sliding fit while said packing element issealed fluid tight with respect to the housing shell, said packingelement having a passage on its internal surface extending from its freeend by which fluid pressure is applied between the packing element andbody tube wall,

an opening through the wall of the body tube to the interior of thepiston cylinder and above the free end of the packing element,

a source of fluid pressure connected to the opening for directapplication to the free end of the packing element in the cylinderformed by the housing shell and for direct application to the centersection of the packing element between the external surface of the bodytube and the packing element through said passage,

whereby the free end of the packing element will be moved toward thefixed end as a piston within the cylinder of the housing shell and thecenter section of the packing element will be simultaneously buckledaway from the body wall without substantial decrease in cross-sectionalthickness of the packing element until a seal is made between the sidesof the well bore and the packing element.

3. A cementing shoe for an oil well including,

a body in the form of a tube adapted to be carried in the well bore onthe end of a pipe string,

`a packing element in the form of a cylinder mounted on the externalsurface of the body tube wall and fixed by one end to the body tubewall,

a housing shell in the form of a cylinder mounted about the outersurface of the body tube wall and spaced from the body tube wallthroughout substantially its entire length and extending inwardly fromone of its two ends to form a seal with respect to the body tube wall,

said shell forming a piston cylinder sized to receive the free end ofthe packing element with a sliding fit while said packing element issealed fluid tight with respect to the housing shell, said packingelement having a passage on its internal surface extending from its freeend by which fluid pressure is applied between the packing element andbody tube wall,

an opening through the Wall of the body tube to the interior of thepiston cylinder and above the free end of the packing element,

a source of fluid pressure arranged for connection to the opening fordirect application to the free end of the packing element in thecylinder formed by the housing shell and for direct application to thecenter section of the packing element between the external surface ofthe body tube and the packing element through said passage,

and means positioned within the body to initially obstruct uid flowthrough the opening and into the interior of the cylinder while thestring of pipe is run in the well bore.

4. A cementing shoe for an oil well including,

a body in the form of a tube adapted to be carried in the well bore onthe end of a pipe string,

a packing element in the form of a cylinder mounted on the externalsurface of the body tube wall and fixed by one end to the body tubewall,

a housing shell in the form of a cylinder mounted about the outersurface of the body tube wall and spaced from the body tube wallVthroughout substantially its entire length and extending inwardly fromone of its 7 two ends to form a seal with respect to the body tube wall,

saidshell forming a piston cylinder sized to receive the free end of thepacking element with a sliding fit while said packing element is sealediluid tight with respect to the housing shell, said packing elementhaving a passage on its internal surface extending from its free end bywhich iluid pressure is applied between the packing element and bodytube wall,

an opening through the wall of the body tube to the interior of thepiston cylinder and above the free end of the packing element,

a source of uid pressure arranged for connection to the opening fordirect application to the free end of the packing element in thecylinder formed by the housing shell and for `direct application to thecenter section of the packing element between the external surface ofthe body tube and the packing element, through said passage,

a valve ring positioned within the body tube and sealed across theopening through the wall of the body tube to prevent iluid from passinginto the interior of the cylinder formed over the packing element by thehousing shell while the string of pipe is run in the well bore,

and a spherical valve member for sealing the valve ring bore in orderfor lluid pressure to be applied to the ring so it will shift in thebody tube and expose the opening through the wall of the body tube tothe fluid pressure.

S. A cementing shoe for an oil Well including,

a body in the form of a tube adapted to be carried in the Well bore onthe end of a pipe string,

a packing element in the form of a cylinder mounted on the externalsurface of the body tube wall and iixed by one end to the body tubewall,

a housing shell in the form of a cylinder mounted about the outersurface of the body tube wall and spaced from the body tube wallthroughout substantially its entire length and extending inwardly fromone of its two ends to form a seal with respect to the body tube wall,

said shell forming a piston cylinder sized to receive the free end ofthe packing element with a sliding t while said packing element issealed fluid tight with respect to the housing shell, said packingelement having a passage on its internal surface extending from its freeend by which fluid pressure is applied between the packing element andbody tube wall,

an opening through the wall of the body tube to the interior of thepiston cylinder and above the free end of the packing element,

a source of fluid pressure arranged for connection to the opening fordirect application to the free end of the packing element in thecylinder formed by the housing shell and for direct application to thecenter section of the packing element between the external surface ofthe body tube and the packing element through said passage to move thefree end toward the `fixed end and the center section into sealinglengagement with the walls of the Well bore,

a valve ring positioned within the body tube and sealed across theopening through the wall of the body tube to prevent iluid from passinginto the interior of the cylinder formed over the packing element by thehousing shell While the string of pipe is run in the well bore,

a spherical valve member for sealing the valve ring bore in order forfluid pressure to be applied to the ring so it will shift in the bodytube and expose the opening through the wall of the body tube to thefluid pressure,

and a check valve arranged within the cylinder formed over the packingelement by the housing shell to prevent the escape of iiuid pressurefrom the cylinder through the opening after the fluid pressure has beenapplied to the opening.

6. A cementing shoe for an oil well including,

a body in the form of a tube adapted to be carried in the well bore onthe end of a pipe string,

a packing element in the form of a cylinder mounted on the externalsurface of the body tube wall and fixed by one end to the body tubewall,

a housing shell in the form of a cylinder mounted about the outersurface of the body tube wall and spaced from the body tube wallthroughout substantially its entire length and extending inwardly fromone of its two ends to form a seal with respect to the body tube wall,

said shell forming a piston cylinder sized to receive the free end ofthe packing element with a sliding tit while said packing element issealed fluid tight with respect to the housing shell, said packingelement having a passage on its internal surface extending from its freeend by which fluid pressure is applied between the packing element andbody tube wall,

a first opening through the wall of the body tube above the location atwhich the housingshell is mounted on the outside wall of the body tube,

a second opening through the wall of the body tube t0 the interior ofthe piston cylinder and above the free end of the packing element,

a shift valve in the form of a cylinder with an opening and initiallypositioned within the body tube to seal on either side of the firstopening through the wall of the body tube while providing a passagealigned with the second opening through the wall of the body tube sofluid pressure can pass through the aligned passage and opening from theinterior of the body tube to the interior of the cylinder formed overthe packing element by the housing shell,

means positioned within the body to initially obstruct fluid flowthrough the aligned passage and second opening while the string of pipeis run in the well bore,

and a source of uid pressure connected to the interior of the body tubefor direct application through the second opening to the free end of thepacking element in the cylinder formed by the housing shell and fordirect application to the center section of the packing element betweenthe external surface of the body tube and the packing element.

7. A cementing shoe for an oil well including,

a body in the form of a tube adapted to be carried in the well bore onthe end of a pipe string,

a packing element in the form of a cylinder mounted on the externalsurface of the body tube wall and lixed by one end to the body tubewall,

a housing shell in the form of a cylinder mounted about the outersurface of the body tube wall and spaced from the body tube wallthroughout substantially its entire length and extending inwardly fromone of its two ends to form a seal with respect to the body tube wall,

said shell forming a piston cylinder sized to receive the free end ofthe packing element with a sliding fit while said packing element issealed fluid tight with respect to the housing shell, said packingelement having a passage on its internal surface extending from its freeend by which fluid pressure is applied between the packing element andbody tube wall,

a rst opening through the Wall of the body tube above the location atwhich the housing shell is mounted on the outside wall of the body tube,

a second opening through the Wall of the body tube to the interior ofthe piston cylinder and above the free end of the packing element, Y

a shift valve in the form of a cylinder with an opening and initiallypositioned within the body tube to seal on either side of the firstopening through the wall of the body tube while providing a passagealigned 9 with the second opening through the Wall of the body tube souid pressure can pass through the aligned passage and opening from theinterior of the body tube to the interior of the cylinder formed overthe packing element by the housing shell,

a valve ring positioned within the shift valve cylinder and sealedacross the passage aligned with the second opening through the wall ofthe body tube to initially obstruct lluid ow through the aligned passageand second opening while the string of pipe is run in the well bore,

a spherical valve member for sealing the valve ring bore in order forfluid pressure to be applied to the valve lring which will shift thering in the body tube and aligned passage to the interior of the bodytube,

and a source of fluid pressure connected to the interior of the bodytube for direct application through the aligned passage and secondopening for direct application to the free end of the packing element inthe cylinder formed by the housing shell and for direct application tothe center of the packing element between the external surface of thebody tube and the packing element to move the free end toward the fixedend and the center section into sealing engagement with the walls of thewell bore.

References Cited in the le of this patent UNITED STATES PATENTS SmithOct. 24, 1939 Johnson July 8, 1952 Renouf Feb. 10, 1959

